Guglielmi said Wilson knew his attackers and they may have been friends at some point. The shooting was not, as previously reported, a home invasion.

"Young people are using guns to settle petty disputes over clothes," Guglielmi said.

Chicago has seen a dramatic rise in the number of shootings and homicides, with August being the deadliest month in the city in two decades. There have been 673 homicides so far this year, including the fatal shootings of the cousin of Chicago Bull Dwyane Wade, a Chicago police officer's son and the son of a famed percussionist.

Davis said in a statement that Wilson's mother was not at home, but Wilson's uncle and three siblings were.

"I grieve for my family. I grieve for the young man who pulled the trigger," Davis said in a statement. "I grieve for his family, his parents, his friends."

Police have not arrested anyone or named any suspects, but Guglielmi said investigators have good leads.

Davis, who was re-elected this month to his 11th term in the 7th Congressional District and is a former Chicago alderman, was in Chicago on Friday and spoke with reporters after talking to police. He wondered how the shooter obtained the gun and said he'd continue to try to combat gun violence.

Davis described his grandson to the newspaper as a "typical 15-year-old" who liked music and basketball, someone who "knew all about ... the stats of different players." But Davis also said he recognized that Chicago's violence problem could affect his family.